Battery life in mobile devices (e.g., smart phones, tablets, handheld computers, other portable devices, etc.) is often a key design constraint. Accordingly, mobile devices are capable of being placed in a lower-power state or “sleep mode.” In this low-power state, generally only minimal circuitry is active, such minimal circuitry including components necessary to sense stimulus for activating higher-power modes of operations. Typically, one of the components remaining active is one or more capacitive microphones, in order to sense for voice activation commands for activating a higher-power state. Often, these microphones consume significant amounts of power, thus reducing battery life of mobile devices.
Another shortcoming of capacitive microphones typically used in mobile devices is that they are typically suited for receiving low-volume sounds with a limited frequency range. However, it may be desirable to record loud sounds, such as a rock concert, which are above the volume range for which most capacitive microphones used in mobile devices are suited. Amplifier circuitry and bias electronics used to amplify electric signals transduced by sound received by such microphones typically draw significant amounts of power, and adapting such circuitry to increase the audio performance of microphones would likely increase power consumption and component cost. Some mobile device manufacturers have overcome this shortcoming by including two capacitive microphones: one adapted for low-volume sound, and one adapted for high-volume sound. However, such a solution may increase cost.